1. Technical Field
The present invention relates to an electrophoretic display device and an electronic apparatus.
2. Related Art
As one type of display devices, there are electrophoretic display devices that perform display by migrating charged particles (electrophoretic particles) that are dispersed in a dispersion medium in accordance with an electric field that is generated between electrodes and controlling the distribution state of the charged particles. Generally, the above-described electrophoretic display devices have structural advantages that the electrophoretic display devices do not need a light source such as a front light due to high reflectivity of the electrophoretic particles and can be formed to be thin and quality advantages that the viewing angle is wide and the contrast is high. In addition, since any back light is not needed, the electrophoretic display devices have an advantage that low power consumption can be implemented, as well. The electrophoretic display devices have attracted attention as next-generation display devices having the above-described devices, and development thereof has been progressed.
For example, in JP-A-2003-84314, an electric potential difference between a pixel electrode and an opposing electrode is generated by storing an image signal in a memory circuit (latch circuit) at once and inputting the image signal stored in the memory circuit to the pixel electrode, and whereby an electrophoretic element is driven. By performing the above-described driving operation, a display image can be maintained based on the image signal that is stored in the latch circuit. In addition, power is not consumed for maintaining an image that is displayed once, and accordingly, lower power consumption is implemented.
However, in the electrophoretic display device, an adhesive agent is used for fixing the electrophoretic elements between the electrodes. The adhesive agent layer formed by using the adhesive agent sometimes includes impurities such as additives for accelerating hardening of the adhesive agent or resolvents thereof. Thus, the adhesive agent layer may sometimes have weak conductivity due to the impurities.
In addition, in order to display an image in the electrophoretic display device, an electric potential difference (for example, about 15 V) required for movement (migration) of electrophoretic particles needs to be supplied between the electrodes that sandwiches the electrophoretic particles. Then, for example, when different colors, for example, a white color and a black color are displayed in adjacent pixels, different electric potentials are applied to the pixel electrodes of the adjacent pixels. In such a case, when the pixel electrodes are connected through the above-described adhesive agent layer having weak conductivity, a leakage current is generated between the adjacent pixel electrodes due to the electric potential difference between the pixel electrodes.
The leakage current generated as described above has a small amount per one spot. However, when the leakage currents are generated in a plurality of spots, the total leakage currents consume large power. For example, when there are many spots in which different colors are displayed in adjacent pixels, as described above, that is, when complicated display is performed, the power consumption increases, and thereby driving at low power consumption, which is one of the advantages of the electrophoretic display device, cannot be performed.
In addition, when a leakage current is generated, electric fields that are generated in edge portions and peripheries of the electrodes are changed. Accordingly, the electrophoretic particles cannot be easily migrated based on the design thereof, and defective display such as display of a gray color that is in the middle of a black color and a white color can easily occur. Therefore, the display quality is degraded.
In addition, the pixel electrode may incur a chemical reaction due to generation of the leakage current. Accordingly, when used for a long time, the pixel electrode deteriorates, and accordingly, display cannot be performed well. Furthermore, the reliability of the electrophoretic display device may be lowered.